CA1095775A - Method and devices for safety for mechanical presses - Google Patents
Method and devices for safety for mechanical pressesInfo
- Publication number
- CA1095775A CA1095775A CA293,909A CA293909A CA1095775A CA 1095775 A CA1095775 A CA 1095775A CA 293909 A CA293909 A CA 293909A CA 1095775 A CA1095775 A CA 1095775A
- Authority
- CA
- Canada
- Prior art keywords
- clutch
- ram
- crankshaft
- press
- ring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
- B30B15/28—Arrangements for preventing distortion of, or damage to, presses or parts thereof
- B30B15/288—Arrangements for preventing distortion of, or damage to, presses or parts thereof preventing over-run or reverse-run of the press shaft
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Control Of Presses (AREA)
- Press Drives And Press Lines (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A mechanical press is provided with means for preventing the ram from repeating an unintended stroke past its uppermost travelling limit after completion of A normal stroke The press includes a ram mounted on a crank shaft for reciprocatory movement along a vertical path between uppermost and lowermost points on such path Motor means are operatively coupled to the crank shaft for turning the crank shaft through 360° rotation including an upper dead center portion A main clutch and brake means are provided for disconnecting the crank shaft from the motor means and stopping the ram at the uppermost point after completion of a stroking cycle when said crank shaft is at the upper dead center portion. Auxillary clutch means are operatively connected in series with the main clutch means the same being normally engaged for transmitting power from the motor means to the crank shaft Means are provided for automatically disengaging the auxiliary clutch means if the crank shaft unintentionally rotates past the upper dead center position upon completion of a stroking cycle of the ram.
A mechanical press is provided with means for preventing the ram from repeating an unintended stroke past its uppermost travelling limit after completion of A normal stroke The press includes a ram mounted on a crank shaft for reciprocatory movement along a vertical path between uppermost and lowermost points on such path Motor means are operatively coupled to the crank shaft for turning the crank shaft through 360° rotation including an upper dead center portion A main clutch and brake means are provided for disconnecting the crank shaft from the motor means and stopping the ram at the uppermost point after completion of a stroking cycle when said crank shaft is at the upper dead center portion. Auxillary clutch means are operatively connected in series with the main clutch means the same being normally engaged for transmitting power from the motor means to the crank shaft Means are provided for automatically disengaging the auxiliary clutch means if the crank shaft unintentionally rotates past the upper dead center position upon completion of a stroking cycle of the ram.
Description
l~aS77S
TITLE OF THE INVENTION
BACKGROUND OF TH~ INVENTION
Field o~ the Inventi:on The present inyention relates generally to mechanical presses for processing workpieces such as metals or other materials and more particularly to a method and devices for safety for mechanical presses.
Description of the Prior A'rt In mechanical presses, a ram holdin~ an upper tool or die is vertically moved in processing operations by means of a crank shaft or eccentric shaft toward and away from a lower tool or die to process workpieces whïch are placed on the lo~er die. For manual operationa in which workpieces are fed onto and removed from the lower die manually by hand, mechanical presses have to be so designed that the ram may be positively stopped at its uppermost travelling limit after completion of each cycle or stroke for working. As is ~ell known, mechanical presses are provided with a clutch and a ~rake which are often provided as an assembly and are mostly pneumatically operated by air, and the ram is stopped when the clutch and the brake are simultaneously operated. Of course, the clutch is so designed as to connect and disconnect the crank shaft for driv-ing the ram with the power source such as a flywheel and a motor, while the brake is operated to stop the crank shaft simultaneously when the clutch disconnects the same with the power source, -In mechanical presses, the trouble has been that the ram often fails to stop at its uppermost travelling limit after a completion of stroke and will repeat another stroke because of malfunction of the clutch and the brake or electric or pneumatic means such as a solenoid operated valve for con-trolling them or for any other reasons. Needless to add, there is a danger of hurting the operator of the press, if the ram repeats an unintended stroke ~ithout stopping at its uppermost travelling limit. Actually, accidents in operations with mechanical pressPs have happened mostly from such unintendedly repeated strokes of the ram.
~ lthough some mechanical presses are doubly equipped ~ith solenoid operated valves for controlling the clutch and the brake for extra safety, of course this arrange-ment could not prevent the ram from unintendedly doubly stroking owing to other troubles than that of the solenoid operated valve. Also, some presses are so constructed that the crank shaft is mechanically and forci~ly stopped ~y a stop means such as a pin from unintendedly rotating past its upper dead center to stop the ram from doubly stroking past its uppermost travelling limit. However, this arrangement not only could not positively prevent the ram from doubly stroking except ~hen the clutch is incompletely connecting the crank shaft with the power source but also it causes the press and its components to be ~roken 109577~
because of the shock occurring when the ram is forcibly stopped.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide a method in which a ram in mechanical presses can be positively and safely stopped from repeating an unintended stroke past its uppermost travelling limit after a completion of a stroke without damaging the press.
It is another object of the present invention to provide a safety device for mechanical presses which can positively and safely stop the ram from repeating an unintended stroke past its uppermost travelling limit after a completion of a stroke without damaging the press.
Basically, these objects are accomplished by providing a press comprising a ram and drive means for effecting working strokes of the ram between a non-working position and a working position, the motion of the drive means being transmitted to the ram by means of a crankshaft which has an upper dead center corresponding to the non-working position of the ram, said drive means incorporating a first clutch operating under normal conditions to engage and disengage the ram from the drive means, the improvement wherein there is provided a normally engaged second clutch means disposed in series with said first clutch means and being capable of disengaging the ram from the drive means, and means for effecting the disengagement of said second clutch means when the crankshaft inadvertently begins to rotate past its upper dead center to prevent the ram inadvertently effecting a working stroke.
~ _ 3 _ E
1a)9577S
In this connection, it is another object of the present invention to provide an au~iliary clutch means for disconnecting the crankshaft from the power source when the main clutch is not positively disengaged at the completion of the stroking cycle.
Other and further objects and advantages of the present invention will be apparent from the following description and accompanying drawings which, by way of illustration, show preferred E
1~S775 embodiments of the present invention and the principle thereof.
B~I~F DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side view of a mechanical press em-bodying the principles of the present invention.
Fig. 2 is a schematic illustration showing an embodiment of the principles of the pres~ent invention.
Fig. 3 is a schematic illustration shDwing the embodiment of Fig. 2 in cross-section along the line III-III of Fig. 2.
Fig. 4 i5 a fragmentary sectional view of the embodiment shown in Figs. 2 and 3.
Fig. 5 is a schematic illustration showing another embodiment of the principles of the present invention.
Fig. 6 is a fragmentary sectional view of the embodiment shown in Fig. 5.
Fig. 7 is a sectional view of the embodiment shown in Figs. 5 and 6 along the line VII-VII of Fig. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Fig. 1, a mechanical press generally designated by the numeral 1 is conventional in that it is constructed of a C-shaped frame 3 and has a worktable 5 on which a lower tool or die (not shown~ is mounted. As is also conven-tional, the press 1 is provided at its front upper portion with a ram 7 which is to be provided at its lower end with an upper tool or die (not shownj and is so mounted as to ~e vertically moved along a guide means 9 ~y a crank shaft or eccentric shaft 11 through a connecting rod 13. Also, the crank shaft 11 for driving the ram 7 is driven in the conventional manner by a motor 15 through a flywheel 17 and a transmission 19 which is 1~:195~75 schematically shown in Fiys. 2 and 5 as including a clutch and brake assembly 21 and having an output gear 23. However, the crank shaft 11 accordin~ to the present invention is different from conventional ones in that it is so constructed as to be connected and disconnected with the output gear 23, as will be described hereinafter. Also, of course the clutch and brake assembly 21 and the output gear 23 can be provided in a manner other than that shown in Figs. 2 and 5. Thus, the ram 7 is vertically lowered by the crank shaft 11 to the worktable 5 to process a workpiece placed thereon when the clutch and brake assembly 21 is worked to transmit the power to the crank shaft 11 in the conventional manner.
As is also conventional, the ram 7 is equipped with counterbalance means 25 ~or counter~alancing the moving weight of the ram 7 and other members attached thereto. The counterbalance means 25 ma~ be of any type, but they are of pneumatic cylinders 27 each having a piston 29 and a piston rod 31 fixed thereto in the preferred embodiment. Also, although two counterbalance means 25 are shown in Figs. 2 and 5, any nu~ber of them may be employed depending upon the type and the size of the press 1. The counterbalance means 25 are mounted to stationary portions on the crown or the uprights of the press 1, and their piston rods 31 are attached to the ram 7 so that they may be moved together therewith. In order to counterbalance the moving weight of the ram 7, the counterbalance means 25 are supplied wit~ air into their chambers 33 from an air source 35 throu~h a conduit 37 which is provided with a reducing valve 39 and a check valve 41. Thus, the ram 7 is counterhalancedhy the counter-balance means 25, and it is lowered to the worktable 5 against 1~5775 the air pressure in the ch~mbers 33 of the counterbalance means 25 so as to process the workpiece. As will ~e understood as the description proceeds, the counter~alance means 25 are most effectively utilized as buffers or shock absorbers to softly stop the ram 7 without ~hock from unintendedly doubly stroking according to the present invention.
Referring to Figs. 2 and 4, the crank shaft 11 is provided at its end adjoining the transmission 19 with a gear 43 which is provided at its inner side with a plurality of radially disposed claws 45. The gear 43 is rotatably mounted on the crank shaft 11 by means of a bearing 47 so as to engage the outpl~t gear 23 of the transmission 19. Also, a clutch ring 49 having a plurality of radially disposed claws 51 is axially slidably provided on the end of the crank shaft 11 adjacent to the gear 43 so that its claws 51 may engage with the claws 45 of the gear 43. It will be understood that the clutch ring 49 having the claws 51 and the claws 45 of the gear 43 act jointly as a so-called dog clutch or claw clutch. As seen from Fig. 4, the clutch ring 49 is so arranged as to slide along a plurality of splines 53 formed on the end of the crank shaft 11 adjacent to the gear 43. ~hus, when t~e claws 51 of the clutch ring 49 is kept in engagement with the cla~s 45 of the gear 43, the crank shaft 11 is rotated by the gear 43 to drive the ram 7, as far as the clutch and brake assembly 21 is transmitting the power from the flywheel 17 to drive the output gear 23. On the other hand, when the clutch ring 49 is slid along the splines 53 on the crank shaft 11 away from the gear 43 to bring its claws 51 out o engagement with the claws 45 thereof, the crank shaft 11 is not driven by the gear 43 any more, even if the clutch and brake assembly 21 goes on transmitting the power.
In order to bring the claws 51 of the clutch ring 49 into or out of engagement with the claws 45 of the gear 43, the clutch rlng 49 is so arranged as to be pneumatically moved by a cylindrical plunger member 55 which may be a piston having a piston rod. As best shown in Fig. 4, the clutch ring 49 is fixed to the plunger member 55 by a pin 57 in such a manner as to radially project there~rom like a flange. ~n the other hand, the plunger member 55 is slidably inserted in an elongate cylindri:al plungercha~mber 59 which i9 formed through the axial center of the end of the crank shaft 11 and is provided at its irlner end opposite to the gear 43 with a radially formed port 61 from which the air is supplied. In this connection, the radial port 61 of the crank shaft 11 is so formed as to right upwardly open when the crank shaft 11 is at its upper dead center to position the ram 7 at its uppermost travelling limit. Also, in order to enable the plunger member 55 and the clutch ring 43 to move together inside and outside the cra~k shaft 11, respectively, the crank shaft 11 is formed at its diametrically opposite portions adjacent to the gear 43 with a pair of axially elongate slots 63 in and along which the pin 57 is movable. Furthermore, the outer end of the plunger chamber 59 is 5'~75 closed by a lid member 65, and a spring 67 is in~erted in the plunger chamber 59 between the plunger mem~er 55 and the lid member 65 to bias the plunger mem~er 55 a~ay from the lid mem-ber 65. Thus, when the plunger chamber 59 is being supplied with the air ~rom the radial port 61l the plunger member 55 is pressed against the spring 67 so as to keep the claws 51 of the clutch ring 49 in contact with the claws ~5 of the gear 43.
On the contrary, on discharge of the air from the plunger chamber 59, the plunger member 55 is moved by the spring 67 so as to bring the clutch ring 49 out of en~agement ~ith t~e claws 45 of the gear 43 to disconnect the crank shaft 11 from the power source.
As best shown in Fig. 4, the crank shaft 11 is journaled in a hub member 69 which is so fixed to a portion of the frame 3 of the press 1 as to hold a portion of the crank shaft 11 where the radial port 61 is formed to outwardly open.
The hub member 69 is formed at its uppermost portion with a vertical inlet port 71 which is bored vertically and radially from the uppermost portion of the hub member 69 toward the axis of the crank shaft 11 on and along a vertical plane where the radial port 61 of the crank shaft 11 is rotated around the axis of the crank shaft 11. It will be readily apparent that the radial port 61 of the crank shaft 11 is connected with the radial inlet port 71 of the hub member 69 when the crank shaft 11 is at its upper dead center where the ram 7 i~ at its uppermost travelling limit, since the radial port 61 is so formed as to be right upwardly open when the crank shaft 11 is at its upper dead center as described hereinbefore.
Also, as shown in Fig. 2, a conduit 73 having a check valve 75 is provided to connect the air source 35 with the port 71. Thus, the plunger chamber 59 is supplied with the air from the l~gS~5 air source 35 through the conduit 73, the inlet port 71 of the hub member 69 and the radial port 61 of the crank shaft 11, each time when the ports 71 and 61 are connected with each other when the crank shaft 11 is rotated to its upper dead center to bring the ram 7 to its uppermost travelling limit.
As shown in Figs. 2 and 3, the hub member 69 is formed, with a radial outlet port 77 which is bored radially toward the axis of the crank shaft 11 at a slight angle " ~ " shown in Fig. 3 to the (with) radial port 71 on and along the same plane as that where the radial port 71 is rotated around the axis of the crank shaft 11. The outlet port 77 is connected by a conduit 79 with a solenoid operated valve 81 which is normally closed. It will be understood that the radial port 61 of the crank shaft 11 is brought into connection with the outlet port 77 of the hub member 69 when the crank shaft 11 is rotated past its upper dead center through the angle ItDC".
The solenoid operated valve 81 is so arranged as to be operated by a limit switch 83 which is workable when touched by a dog 85 fixed to a portion of the crank shaft 11. The limit switch 83 is so disposed as to be actuated by the dog 85 when the crank shaft 11 is rotated past its upper dead center through an angle " ,e " which is smaller than the angle l! ClC 11 of the outlet port 77 as shown in Fig. 3.
Also, the limit switch 83 is so arranged in a well-known manner as to be actuated by the dog 85 not when the crank shaft 11 is normally rotated but only when the crank shaft 11 is unintendedly rotated past its upper dead center to repeatedly move the ram 7 after a completion of its stroke without stopping at its uppermost travelling limit.
From the ahove description, it will be now under-stood that the ram 7 is stopped from unintendedly doubly stroking as soon as the crank shaft 11 be~ins to unintendedly rotate past its upper dead center. Of course, the crank shaft 11 is rotated by the clutch ring 49 in normal operations since the plunger member 55 is pushed to keep the clutch rin~ 4~ in engagement with the claws ~5 of the ~ear 43 b~ the air supplied into the plunger chamber 59 from the conduit 73. When the crank shaft 11 is unintendedly rotated through the angle "B" shown in Fig. 3 past its upper dead center, the limit s~itch 83 is actuated by the dog 85 in a well-known manner to make the solenoid operated valve 81 open. As the result, when the cran~ sha~t 11 is rotated through the angle '~" to bring its radial port 61 into connection with the outlet port 77 of the hub member 69, the air acting on the plunger 55 in the plunger chamber 59 will be exhausted to the atmosphere through t~e conduit 79 and the sole-noid operated valve 81. On exhaustion of the air from the plunger chamber 59, the plunger 55 is moved by the spring 67 to bring the clutch rlng 4~ out of engagement with the claws 45 of the gear 43. Accordingly, the crank shaft 11 is disconnected from the power source such as the gear 43 and is stopped from driving the ram 7, even if the clutch and brake assembly 21 is transmitting the power. As the result, the ram 7 is softly stopped without shock from lowering by the air acting in the counterbalance means 25, although it is going to lower by inertia.
Thus, it will be appreciated that the counterbalance means 25 act as buffers or shock-absorbers to softly or shocklessly stop the ram 7 against inertia without damaging any portion of the press 1 af~er the crank shaft 11 is disconnected from the power source.
Aside from Figs. 2 - 4, the advantages of the present invention are also at~ainable with the second embodiment l~9S'775 illustrated in ~igs. 5 - 7. The second embodiment will be des-cri~ed with use of the same numerals as the first embodiment shown in Fiqs. 2-4 with regard to the elements common to both embodiments.
Referring to Figs,5 and 6, the crank shaft 11 shown as an eccentric shaft in the preferred embodiment is rotatably mounted on the ram 7 by rneans of bearîngs 87 and it is provided at its end adjoining the transmission 19 with a ring member 89 which is fixed thereto by a key 91 but may be formed as a flange thereon. As seen from Fig. 6, the ring member 89 is formed at its inner face with a plurality of radial depres-sions 89d which are equally spaced from each other and are formed to radially extend with equal widths so that a plurality of sector-like projections 89p are formed therebetween. An annular gear 93 is freely rotatably mounted on and around the ring member 89 by means of an annular bearing or brushing 94 so as to engage the output gear 23 of the transmission 19. As seen from Fig. 6, in order to hold the annular gear 93 on the ring member 89, the ring member 89 and the annular gear 93 are formed at their inner circumferential edges with a covex annular step and a concave annular step, respectively. The annular gear 93 is also formed at its inner face with a plurality of radial depressions 93d which are equally spaced from each other and are formed to radially extend with the same widths as the depressions 89d of the ring member 89 so that a plurality of sector-like projections 93p are formed therebetween. Also, a clutch ring 95 is provided around the crank shaft 11 in such a manner as to face with the depressions 89d and 93d and the projections 89p and S3p of the ring member 89 and the annular 3~ gear 93. The clutch ring 95 is provided at its face on the side of the ring member 89 and the annular gear 93 with a plurality of elongate claw members 97 which are as many as the depressions ~9S775 89d and 53d of the rin~ member 89 and the annular gear 93.
As seen from Fig. 7, the claw mem~.ers 97 of the clutch ring 95 are equal in width to the depressions 89d and 93d of the ring mRmber 89 and the annular gear g3 and equal in length to the added radial lengths of both of them. More particularly, the claw members 97 of the clutch ring g5 are radially arranged on the face of the clutch ring 95 so t~at they may be fitted in both the depressions ~9d and 93d of the ring mem~er 89 and the annular gear 93 to connect them with each other. It will be readily understood that when the clutch mem~ers 97 of the clutch ring 95 are engaged with both the depressions 89d and 93d of the ring memker 89 and the annulargear 93r the crank shaft 11 is rotated by the output gear 23 through the annular gear 93, the clutch ring 95 and the ring member 89.
As best shown in Fis. 6, the ring mem~er 89 is formed at its outer side opposite to its depressions 8~d with an annular chamber 99 which has an equal width throughout its length and depth and extends circumferentially at an equal radial distance from the axis of the crank shaft 11.
20 An annular piston mem~er 101 having seal mem~ers 103 is slidably inserted in the annular chamber 99 ~o that it may be moved in the axial direction of th~ crank shaft 11. The annular piston member 101 is integrally connected with the clutch ring 95 by a plurality of elongate bolts 105 and cylindrical spacers 107 through bores 109 which are formed through the rin~ member 89 from the end of the annular chamber 99 in parallel with and at an equal radial distance from the axis of the crank shaft 11.
More particularly, the elongate bolts 105 are inserted through the annular piston member 101, the cylindrical spacers 107 and the clutch ring 95 tc integrally connect them all, and the cylindrical spacers 107 are slidably inserted in the bores 109.
Also, a disk plate 111 is fixed to the ring member ~9 by a ~095775 plurality of kolts 113 to cover the end of the crank shaft 11 and hold the annular gear 93 in position on the ring memher 89.
As shown in Fig. 6, the disk plate 111 is formed with a plurality of openings 115 to allow the ends of the elongate bolts 105 to project out. Thus, when t~e annular cham~er 99 is supplied with the air, the annular piston mem~er 1~1 is moved in t~e annular chamber 99 to pull the clutch ring 95 by means of the elongate bolts 105 and the cylindrical spacers lQ7 so as to bring the claw memhers 97 of the clutch ring 95 into engagement 10 with the depressions 89d and 93d of the ring member 89 and the annular gear 93.
As best seen from Fig. 6, a plurality of springs 117 are provided between the clutch ring 95 and the ring member 89 to bias the clutch ring 95 away from the ring member 89. In the preferred embodiment, the springs 117 are inserted in a plurality o:E bores 119 which are formed in the ring member 89 on its side facing with the clutch ring 95 in parallel with and at an e~ual xadial distance from the axis of the crank shaft 11. Thus, the clutch ring 95 is pushed by the springs 117 away from the ring member 89 and the annular gear 93 to bring its claw members 97 out of engagement with t~eir depressions 89d and 93d, when the air acting on the annular piston member 101 is exhausted from the annular chamber 99.
In order to supply and discharge the air into and from the annular chamber 93, there are provided a plurality of passages 121 which are formed through the ring member 89 to connect with the annular chamber 99. The passages 121 are connected with an elongate bore 123 which is formed through the axis of the crank shaft 11. In the preferred embodiment as shown in Fig. 6, the passages 121 are connected with the elongate bore 123 by a plurality of grooves 125 which ar~ formed on the inner side of the disk plate 111 in such a manner as to radially ~09S775 extend from the end of the elongate ~ore 123 o~ the crank shaft 11. Therefore, the passages 121 are so ~ormed as to rather radially extend from the annular chamber 99 to open to the radial inner circumference o~ the ring mem~er 89 on the side of the disk plate 111. In this connect~on, a single one of the passages 121 and a single one of the grooves 125 may be provided for the plural~ty of them.
As shown in Figs. 5 and 6, the elongate bore 123 is connected at its end opposite to the grooves 125 with a swivel joint 127 with which a conduit 129 is connected from the air source 35 through a solenoid operated valve 131. As seen from Fig. 5, the solenoid operated valve 131 is so arranged as to supply the air from the air source 35 normally when not energized and exhaust the air to the atmosphere when energized. Also, the solenoid operated valve 131 is so arranged as to be energized by a limit switch 83' which is workable when touched by a dog 85' which is fixed to a portion of the crank shaft 11. The limit switch 83' is so arranged as to be actuated by the dog 85' to energize the solenoid operated valve 131 only when the crank shaft 11 has begun to unintendedly rotate past its upper dead center after a completion of a stroke of the ram 7 in all the same manner as the embodiment shown in Figs. 2, 3 and 4. Thus, normally the air from the air source 35 is supplied from the conduit 129 through the swivel joint 127, the elongate bore 123, the grooves 125 and the passages 121 into the annular chamber 99 to enable the annular piston member 101 to hold the claw members 97 of the clutch ring 95 in engagement with the depressions 89d and 93d of the ring member 89 and the annular gear 93. However, once the crank shaft 11 has begun to rotate past its upper dead center, the solenoid operated valve 131 is energized by the limit switch 83' to allow the air to exhaust therethrou~h, and accordingly the springs 117 will push the clutch 577,~
ring 95 to pull the cla~ me~er~ 97 out o~ enga~ement with the depresslons 89d and 93d of the ri~ng member 89 and the annular gear 93, As shown in Fig. 6, a limit switch 133 and a dog mem-ber 135 are provided on a portion of the frame 3 of the press 1 in the vicinity of the clutch ring 95. The limit switch 133 is so arranged as to stop t~e motor 15 when touched by the dog mem-ber 135, while the dog mem~er 135 is so provided as to be pushed by the clutch ring 95 into contact with the limit switch 133 when the clutch ring 95 is moved out of engagement with the de-pressions 39d and 93d of the ring member 89 and the annular gear 93. In the preferred embodiment, the dog member 135 is slidably inserted in a cylindrical case 137 horizontally fixed to the frame 3 of the press 1 and is biased by a spring 139 toward the clutch ring 95, and it is provided at its end with a roller 141 to be touched by the clutch ring 9S. Thus, when the clutch ring 95 is moved out of engagement with the ring member 89 and the annular gear 93 to disconnect the crank shaft 11 from the power source, the dog member 135 is pushed by the clutch ring 95 into contact with the limit s~itch 133 to stop the motor 15 from driving the press 1. Accordingly, once the crank shaft 11 has begun to unintendedly rotate past its upper dead center to allow the ram 7 to unintendedly doubly stroke, not only the crank shaft 11 i5 stopped from being driven by the annular gear 93 but also the press 1 is completely stopped from being driven by the motor 15.
Referring to Figs. 5 and 6, in order to align radial-ly the annular gear 93 in phase with the clutch ring 95, a proximity switch 143 is provided in the vicinity of the annular gear 33 on a bracket 145 fixed to a portion of the frame 3 of the press 1, and an actuating member 14~ for actuating the proximity switch 143 is fixed to the radially outer edge of the outer side of the annul~r gear 93. In the well-known manner, the proximity switch 143 is so arran~ed as to make a slgnal when the actuating member 147 is in the proximity thereof.
Therefore, the actuatin~ member 147 i5 SO located on the annular gear 45 that it may be in the proximity o~ the proximity switch 143 when the claw mem~ers 97 of the clutch ring 95 are in engage-ment with the depressions 89d and 93d o~ the ring member 89 and the annular gear 93 with the crank shaft 11 put in a pre-deter-mined rotational position. Thus, in order to align radially the annular gear 93 in phase with the clutch ring 95 it is only necessary to firstly rotate the crank shaft 11 to the pre-determined rotational posi~ion and then rotate the annular gear 93 on the ring member 89 until the proximity switch 143 signals that the actuating member 14~ has come into the proximity there-of. Incidentally, it is necessary to align radially the clutch ring 95 in phase with the annular gear 93 after the clutch ring 95 has been moved out of engagement with the depressions 89d and 93d of the ring member 89 and the annular gear 93.
As is now apparsnt from the above description, the ram 7 is softly or shocklessly stopped by the counterbalance - means 25 from unintendedly doubly stroking after a completion ,~ of a stroking cycle as soon as the crank shaft 11 begins to rotate past its upper dead center in the second embodiment too. When the crank shaft 11 unintendedly begins to rotate past its upper dead center and the limit switch 83l is actuated by the dog 85' in the same well-known manner as in the first embodiment, the solenoid operated valve 131 is energized to allow the air pre-ssurized in the annular chamber 99 to exhaust therefrom through the passages 121, the grooves 125, the elongate bore 123 of 30 the crank shaft 11 and the swivel joint 127. Accordingly, the annular piston member 101 cannot pull the clutch ring 95 against the springs 117 any more and the clutch ring 95 is pushed by the ~9577S
springs 117 to bring the claw members 97 out of engagement with the depressions 8gd and 93d of the ring member 89 and the annular gear 93. As the result, the ring member~89 is disconnected from the annular gear 93 to stop driving the crank shaft 11, and according-ly the ram 7 is driven no more by the crank shaft 11 and is softly or shocklessly stoppea from doubly stroking by the counterbalance means 25 without damaging any portion of the press 1. Also, as soon as the clutch ring 95 is pushed by the springs 117 away from the ring member 89 and the annular gear 93, the dog member 135 is pushed thereby into contact with the limit switch 133 to stop the motor 15 out of motion. Furthermore, the annular gear 93 and the clutch ring 95 can be radially aligned in phase with each other by firstly putting the crank shaft 11 to a pre-determined rota-tional position and then rotating the annular gear 93 until the ~-actuating member 147 is brought into the proximity of the proxi-mity switch 143.
As has been so far described, according to the present invention, the crank shaft 11 is disconnect from the power source in case that it begins to unintendedly rotate past its upper dead center to allow the ram 7 to doubly stroke after a com-pletion of a stroke. Also, on disconnection of the crank shaft 11 from the power source, the ram 7 is softly or shocklessly stopped from doubly stroking by the counterbalance means 25 without damaging any portion of the press 1.
Although a preferred form of the present invention has been illustrated and described, it should be understood that the device is capable of modification by one skilled in the art without departing from the principles of the invention. Accordingly, the scope of the invention is to be limited only by the claims append-ed hereto.
TITLE OF THE INVENTION
BACKGROUND OF TH~ INVENTION
Field o~ the Inventi:on The present inyention relates generally to mechanical presses for processing workpieces such as metals or other materials and more particularly to a method and devices for safety for mechanical presses.
Description of the Prior A'rt In mechanical presses, a ram holdin~ an upper tool or die is vertically moved in processing operations by means of a crank shaft or eccentric shaft toward and away from a lower tool or die to process workpieces whïch are placed on the lo~er die. For manual operationa in which workpieces are fed onto and removed from the lower die manually by hand, mechanical presses have to be so designed that the ram may be positively stopped at its uppermost travelling limit after completion of each cycle or stroke for working. As is ~ell known, mechanical presses are provided with a clutch and a ~rake which are often provided as an assembly and are mostly pneumatically operated by air, and the ram is stopped when the clutch and the brake are simultaneously operated. Of course, the clutch is so designed as to connect and disconnect the crank shaft for driv-ing the ram with the power source such as a flywheel and a motor, while the brake is operated to stop the crank shaft simultaneously when the clutch disconnects the same with the power source, -In mechanical presses, the trouble has been that the ram often fails to stop at its uppermost travelling limit after a completion of stroke and will repeat another stroke because of malfunction of the clutch and the brake or electric or pneumatic means such as a solenoid operated valve for con-trolling them or for any other reasons. Needless to add, there is a danger of hurting the operator of the press, if the ram repeats an unintended stroke ~ithout stopping at its uppermost travelling limit. Actually, accidents in operations with mechanical pressPs have happened mostly from such unintendedly repeated strokes of the ram.
~ lthough some mechanical presses are doubly equipped ~ith solenoid operated valves for controlling the clutch and the brake for extra safety, of course this arrange-ment could not prevent the ram from unintendedly doubly stroking owing to other troubles than that of the solenoid operated valve. Also, some presses are so constructed that the crank shaft is mechanically and forci~ly stopped ~y a stop means such as a pin from unintendedly rotating past its upper dead center to stop the ram from doubly stroking past its uppermost travelling limit. However, this arrangement not only could not positively prevent the ram from doubly stroking except ~hen the clutch is incompletely connecting the crank shaft with the power source but also it causes the press and its components to be ~roken 109577~
because of the shock occurring when the ram is forcibly stopped.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide a method in which a ram in mechanical presses can be positively and safely stopped from repeating an unintended stroke past its uppermost travelling limit after a completion of a stroke without damaging the press.
It is another object of the present invention to provide a safety device for mechanical presses which can positively and safely stop the ram from repeating an unintended stroke past its uppermost travelling limit after a completion of a stroke without damaging the press.
Basically, these objects are accomplished by providing a press comprising a ram and drive means for effecting working strokes of the ram between a non-working position and a working position, the motion of the drive means being transmitted to the ram by means of a crankshaft which has an upper dead center corresponding to the non-working position of the ram, said drive means incorporating a first clutch operating under normal conditions to engage and disengage the ram from the drive means, the improvement wherein there is provided a normally engaged second clutch means disposed in series with said first clutch means and being capable of disengaging the ram from the drive means, and means for effecting the disengagement of said second clutch means when the crankshaft inadvertently begins to rotate past its upper dead center to prevent the ram inadvertently effecting a working stroke.
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1a)9577S
In this connection, it is another object of the present invention to provide an au~iliary clutch means for disconnecting the crankshaft from the power source when the main clutch is not positively disengaged at the completion of the stroking cycle.
Other and further objects and advantages of the present invention will be apparent from the following description and accompanying drawings which, by way of illustration, show preferred E
1~S775 embodiments of the present invention and the principle thereof.
B~I~F DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side view of a mechanical press em-bodying the principles of the present invention.
Fig. 2 is a schematic illustration showing an embodiment of the principles of the pres~ent invention.
Fig. 3 is a schematic illustration shDwing the embodiment of Fig. 2 in cross-section along the line III-III of Fig. 2.
Fig. 4 i5 a fragmentary sectional view of the embodiment shown in Figs. 2 and 3.
Fig. 5 is a schematic illustration showing another embodiment of the principles of the present invention.
Fig. 6 is a fragmentary sectional view of the embodiment shown in Fig. 5.
Fig. 7 is a sectional view of the embodiment shown in Figs. 5 and 6 along the line VII-VII of Fig. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Fig. 1, a mechanical press generally designated by the numeral 1 is conventional in that it is constructed of a C-shaped frame 3 and has a worktable 5 on which a lower tool or die (not shown~ is mounted. As is also conven-tional, the press 1 is provided at its front upper portion with a ram 7 which is to be provided at its lower end with an upper tool or die (not shownj and is so mounted as to ~e vertically moved along a guide means 9 ~y a crank shaft or eccentric shaft 11 through a connecting rod 13. Also, the crank shaft 11 for driving the ram 7 is driven in the conventional manner by a motor 15 through a flywheel 17 and a transmission 19 which is 1~:195~75 schematically shown in Fiys. 2 and 5 as including a clutch and brake assembly 21 and having an output gear 23. However, the crank shaft 11 accordin~ to the present invention is different from conventional ones in that it is so constructed as to be connected and disconnected with the output gear 23, as will be described hereinafter. Also, of course the clutch and brake assembly 21 and the output gear 23 can be provided in a manner other than that shown in Figs. 2 and 5. Thus, the ram 7 is vertically lowered by the crank shaft 11 to the worktable 5 to process a workpiece placed thereon when the clutch and brake assembly 21 is worked to transmit the power to the crank shaft 11 in the conventional manner.
As is also conventional, the ram 7 is equipped with counterbalance means 25 ~or counter~alancing the moving weight of the ram 7 and other members attached thereto. The counterbalance means 25 ma~ be of any type, but they are of pneumatic cylinders 27 each having a piston 29 and a piston rod 31 fixed thereto in the preferred embodiment. Also, although two counterbalance means 25 are shown in Figs. 2 and 5, any nu~ber of them may be employed depending upon the type and the size of the press 1. The counterbalance means 25 are mounted to stationary portions on the crown or the uprights of the press 1, and their piston rods 31 are attached to the ram 7 so that they may be moved together therewith. In order to counterbalance the moving weight of the ram 7, the counterbalance means 25 are supplied wit~ air into their chambers 33 from an air source 35 throu~h a conduit 37 which is provided with a reducing valve 39 and a check valve 41. Thus, the ram 7 is counterhalancedhy the counter-balance means 25, and it is lowered to the worktable 5 against 1~5775 the air pressure in the ch~mbers 33 of the counterbalance means 25 so as to process the workpiece. As will ~e understood as the description proceeds, the counter~alance means 25 are most effectively utilized as buffers or shock absorbers to softly stop the ram 7 without ~hock from unintendedly doubly stroking according to the present invention.
Referring to Figs. 2 and 4, the crank shaft 11 is provided at its end adjoining the transmission 19 with a gear 43 which is provided at its inner side with a plurality of radially disposed claws 45. The gear 43 is rotatably mounted on the crank shaft 11 by means of a bearing 47 so as to engage the outpl~t gear 23 of the transmission 19. Also, a clutch ring 49 having a plurality of radially disposed claws 51 is axially slidably provided on the end of the crank shaft 11 adjacent to the gear 43 so that its claws 51 may engage with the claws 45 of the gear 43. It will be understood that the clutch ring 49 having the claws 51 and the claws 45 of the gear 43 act jointly as a so-called dog clutch or claw clutch. As seen from Fig. 4, the clutch ring 49 is so arranged as to slide along a plurality of splines 53 formed on the end of the crank shaft 11 adjacent to the gear 43. ~hus, when t~e claws 51 of the clutch ring 49 is kept in engagement with the cla~s 45 of the gear 43, the crank shaft 11 is rotated by the gear 43 to drive the ram 7, as far as the clutch and brake assembly 21 is transmitting the power from the flywheel 17 to drive the output gear 23. On the other hand, when the clutch ring 49 is slid along the splines 53 on the crank shaft 11 away from the gear 43 to bring its claws 51 out o engagement with the claws 45 thereof, the crank shaft 11 is not driven by the gear 43 any more, even if the clutch and brake assembly 21 goes on transmitting the power.
In order to bring the claws 51 of the clutch ring 49 into or out of engagement with the claws 45 of the gear 43, the clutch rlng 49 is so arranged as to be pneumatically moved by a cylindrical plunger member 55 which may be a piston having a piston rod. As best shown in Fig. 4, the clutch ring 49 is fixed to the plunger member 55 by a pin 57 in such a manner as to radially project there~rom like a flange. ~n the other hand, the plunger member 55 is slidably inserted in an elongate cylindri:al plungercha~mber 59 which i9 formed through the axial center of the end of the crank shaft 11 and is provided at its irlner end opposite to the gear 43 with a radially formed port 61 from which the air is supplied. In this connection, the radial port 61 of the crank shaft 11 is so formed as to right upwardly open when the crank shaft 11 is at its upper dead center to position the ram 7 at its uppermost travelling limit. Also, in order to enable the plunger member 55 and the clutch ring 43 to move together inside and outside the cra~k shaft 11, respectively, the crank shaft 11 is formed at its diametrically opposite portions adjacent to the gear 43 with a pair of axially elongate slots 63 in and along which the pin 57 is movable. Furthermore, the outer end of the plunger chamber 59 is 5'~75 closed by a lid member 65, and a spring 67 is in~erted in the plunger chamber 59 between the plunger mem~er 55 and the lid member 65 to bias the plunger mem~er 55 a~ay from the lid mem-ber 65. Thus, when the plunger chamber 59 is being supplied with the air ~rom the radial port 61l the plunger member 55 is pressed against the spring 67 so as to keep the claws 51 of the clutch ring 49 in contact with the claws ~5 of the gear 43.
On the contrary, on discharge of the air from the plunger chamber 59, the plunger member 55 is moved by the spring 67 so as to bring the clutch ring 49 out of en~agement ~ith t~e claws 45 of the gear 43 to disconnect the crank shaft 11 from the power source.
As best shown in Fig. 4, the crank shaft 11 is journaled in a hub member 69 which is so fixed to a portion of the frame 3 of the press 1 as to hold a portion of the crank shaft 11 where the radial port 61 is formed to outwardly open.
The hub member 69 is formed at its uppermost portion with a vertical inlet port 71 which is bored vertically and radially from the uppermost portion of the hub member 69 toward the axis of the crank shaft 11 on and along a vertical plane where the radial port 61 of the crank shaft 11 is rotated around the axis of the crank shaft 11. It will be readily apparent that the radial port 61 of the crank shaft 11 is connected with the radial inlet port 71 of the hub member 69 when the crank shaft 11 is at its upper dead center where the ram 7 i~ at its uppermost travelling limit, since the radial port 61 is so formed as to be right upwardly open when the crank shaft 11 is at its upper dead center as described hereinbefore.
Also, as shown in Fig. 2, a conduit 73 having a check valve 75 is provided to connect the air source 35 with the port 71. Thus, the plunger chamber 59 is supplied with the air from the l~gS~5 air source 35 through the conduit 73, the inlet port 71 of the hub member 69 and the radial port 61 of the crank shaft 11, each time when the ports 71 and 61 are connected with each other when the crank shaft 11 is rotated to its upper dead center to bring the ram 7 to its uppermost travelling limit.
As shown in Figs. 2 and 3, the hub member 69 is formed, with a radial outlet port 77 which is bored radially toward the axis of the crank shaft 11 at a slight angle " ~ " shown in Fig. 3 to the (with) radial port 71 on and along the same plane as that where the radial port 71 is rotated around the axis of the crank shaft 11. The outlet port 77 is connected by a conduit 79 with a solenoid operated valve 81 which is normally closed. It will be understood that the radial port 61 of the crank shaft 11 is brought into connection with the outlet port 77 of the hub member 69 when the crank shaft 11 is rotated past its upper dead center through the angle ItDC".
The solenoid operated valve 81 is so arranged as to be operated by a limit switch 83 which is workable when touched by a dog 85 fixed to a portion of the crank shaft 11. The limit switch 83 is so disposed as to be actuated by the dog 85 when the crank shaft 11 is rotated past its upper dead center through an angle " ,e " which is smaller than the angle l! ClC 11 of the outlet port 77 as shown in Fig. 3.
Also, the limit switch 83 is so arranged in a well-known manner as to be actuated by the dog 85 not when the crank shaft 11 is normally rotated but only when the crank shaft 11 is unintendedly rotated past its upper dead center to repeatedly move the ram 7 after a completion of its stroke without stopping at its uppermost travelling limit.
From the ahove description, it will be now under-stood that the ram 7 is stopped from unintendedly doubly stroking as soon as the crank shaft 11 be~ins to unintendedly rotate past its upper dead center. Of course, the crank shaft 11 is rotated by the clutch ring 49 in normal operations since the plunger member 55 is pushed to keep the clutch rin~ 4~ in engagement with the claws ~5 of the ~ear 43 b~ the air supplied into the plunger chamber 59 from the conduit 73. When the crank shaft 11 is unintendedly rotated through the angle "B" shown in Fig. 3 past its upper dead center, the limit s~itch 83 is actuated by the dog 85 in a well-known manner to make the solenoid operated valve 81 open. As the result, when the cran~ sha~t 11 is rotated through the angle '~" to bring its radial port 61 into connection with the outlet port 77 of the hub member 69, the air acting on the plunger 55 in the plunger chamber 59 will be exhausted to the atmosphere through t~e conduit 79 and the sole-noid operated valve 81. On exhaustion of the air from the plunger chamber 59, the plunger 55 is moved by the spring 67 to bring the clutch rlng 4~ out of engagement with the claws 45 of the gear 43. Accordingly, the crank shaft 11 is disconnected from the power source such as the gear 43 and is stopped from driving the ram 7, even if the clutch and brake assembly 21 is transmitting the power. As the result, the ram 7 is softly stopped without shock from lowering by the air acting in the counterbalance means 25, although it is going to lower by inertia.
Thus, it will be appreciated that the counterbalance means 25 act as buffers or shock-absorbers to softly or shocklessly stop the ram 7 against inertia without damaging any portion of the press 1 af~er the crank shaft 11 is disconnected from the power source.
Aside from Figs. 2 - 4, the advantages of the present invention are also at~ainable with the second embodiment l~9S'775 illustrated in ~igs. 5 - 7. The second embodiment will be des-cri~ed with use of the same numerals as the first embodiment shown in Fiqs. 2-4 with regard to the elements common to both embodiments.
Referring to Figs,5 and 6, the crank shaft 11 shown as an eccentric shaft in the preferred embodiment is rotatably mounted on the ram 7 by rneans of bearîngs 87 and it is provided at its end adjoining the transmission 19 with a ring member 89 which is fixed thereto by a key 91 but may be formed as a flange thereon. As seen from Fig. 6, the ring member 89 is formed at its inner face with a plurality of radial depres-sions 89d which are equally spaced from each other and are formed to radially extend with equal widths so that a plurality of sector-like projections 89p are formed therebetween. An annular gear 93 is freely rotatably mounted on and around the ring member 89 by means of an annular bearing or brushing 94 so as to engage the output gear 23 of the transmission 19. As seen from Fig. 6, in order to hold the annular gear 93 on the ring member 89, the ring member 89 and the annular gear 93 are formed at their inner circumferential edges with a covex annular step and a concave annular step, respectively. The annular gear 93 is also formed at its inner face with a plurality of radial depressions 93d which are equally spaced from each other and are formed to radially extend with the same widths as the depressions 89d of the ring member 89 so that a plurality of sector-like projections 93p are formed therebetween. Also, a clutch ring 95 is provided around the crank shaft 11 in such a manner as to face with the depressions 89d and 93d and the projections 89p and S3p of the ring member 89 and the annular 3~ gear 93. The clutch ring 95 is provided at its face on the side of the ring member 89 and the annular gear 93 with a plurality of elongate claw members 97 which are as many as the depressions ~9S775 89d and 53d of the rin~ member 89 and the annular gear 93.
As seen from Fig. 7, the claw mem~.ers 97 of the clutch ring 95 are equal in width to the depressions 89d and 93d of the ring mRmber 89 and the annular gear g3 and equal in length to the added radial lengths of both of them. More particularly, the claw members 97 of the clutch ring g5 are radially arranged on the face of the clutch ring 95 so t~at they may be fitted in both the depressions ~9d and 93d of the ring mem~er 89 and the annular gear 93 to connect them with each other. It will be readily understood that when the clutch mem~ers 97 of the clutch ring 95 are engaged with both the depressions 89d and 93d of the ring memker 89 and the annulargear 93r the crank shaft 11 is rotated by the output gear 23 through the annular gear 93, the clutch ring 95 and the ring member 89.
As best shown in Fis. 6, the ring mem~er 89 is formed at its outer side opposite to its depressions 8~d with an annular chamber 99 which has an equal width throughout its length and depth and extends circumferentially at an equal radial distance from the axis of the crank shaft 11.
20 An annular piston mem~er 101 having seal mem~ers 103 is slidably inserted in the annular chamber 99 ~o that it may be moved in the axial direction of th~ crank shaft 11. The annular piston member 101 is integrally connected with the clutch ring 95 by a plurality of elongate bolts 105 and cylindrical spacers 107 through bores 109 which are formed through the rin~ member 89 from the end of the annular chamber 99 in parallel with and at an equal radial distance from the axis of the crank shaft 11.
More particularly, the elongate bolts 105 are inserted through the annular piston member 101, the cylindrical spacers 107 and the clutch ring 95 tc integrally connect them all, and the cylindrical spacers 107 are slidably inserted in the bores 109.
Also, a disk plate 111 is fixed to the ring member ~9 by a ~095775 plurality of kolts 113 to cover the end of the crank shaft 11 and hold the annular gear 93 in position on the ring memher 89.
As shown in Fig. 6, the disk plate 111 is formed with a plurality of openings 115 to allow the ends of the elongate bolts 105 to project out. Thus, when t~e annular cham~er 99 is supplied with the air, the annular piston mem~er 1~1 is moved in t~e annular chamber 99 to pull the clutch ring 95 by means of the elongate bolts 105 and the cylindrical spacers lQ7 so as to bring the claw memhers 97 of the clutch ring 95 into engagement 10 with the depressions 89d and 93d of the ring member 89 and the annular gear 93.
As best seen from Fig. 6, a plurality of springs 117 are provided between the clutch ring 95 and the ring member 89 to bias the clutch ring 95 away from the ring member 89. In the preferred embodiment, the springs 117 are inserted in a plurality o:E bores 119 which are formed in the ring member 89 on its side facing with the clutch ring 95 in parallel with and at an e~ual xadial distance from the axis of the crank shaft 11. Thus, the clutch ring 95 is pushed by the springs 117 away from the ring member 89 and the annular gear 93 to bring its claw members 97 out of engagement with t~eir depressions 89d and 93d, when the air acting on the annular piston member 101 is exhausted from the annular chamber 99.
In order to supply and discharge the air into and from the annular chamber 93, there are provided a plurality of passages 121 which are formed through the ring member 89 to connect with the annular chamber 99. The passages 121 are connected with an elongate bore 123 which is formed through the axis of the crank shaft 11. In the preferred embodiment as shown in Fig. 6, the passages 121 are connected with the elongate bore 123 by a plurality of grooves 125 which ar~ formed on the inner side of the disk plate 111 in such a manner as to radially ~09S775 extend from the end of the elongate ~ore 123 o~ the crank shaft 11. Therefore, the passages 121 are so ~ormed as to rather radially extend from the annular chamber 99 to open to the radial inner circumference o~ the ring mem~er 89 on the side of the disk plate 111. In this connect~on, a single one of the passages 121 and a single one of the grooves 125 may be provided for the plural~ty of them.
As shown in Figs. 5 and 6, the elongate bore 123 is connected at its end opposite to the grooves 125 with a swivel joint 127 with which a conduit 129 is connected from the air source 35 through a solenoid operated valve 131. As seen from Fig. 5, the solenoid operated valve 131 is so arranged as to supply the air from the air source 35 normally when not energized and exhaust the air to the atmosphere when energized. Also, the solenoid operated valve 131 is so arranged as to be energized by a limit switch 83' which is workable when touched by a dog 85' which is fixed to a portion of the crank shaft 11. The limit switch 83' is so arranged as to be actuated by the dog 85' to energize the solenoid operated valve 131 only when the crank shaft 11 has begun to unintendedly rotate past its upper dead center after a completion of a stroke of the ram 7 in all the same manner as the embodiment shown in Figs. 2, 3 and 4. Thus, normally the air from the air source 35 is supplied from the conduit 129 through the swivel joint 127, the elongate bore 123, the grooves 125 and the passages 121 into the annular chamber 99 to enable the annular piston member 101 to hold the claw members 97 of the clutch ring 95 in engagement with the depressions 89d and 93d of the ring member 89 and the annular gear 93. However, once the crank shaft 11 has begun to rotate past its upper dead center, the solenoid operated valve 131 is energized by the limit switch 83' to allow the air to exhaust therethrou~h, and accordingly the springs 117 will push the clutch 577,~
ring 95 to pull the cla~ me~er~ 97 out o~ enga~ement with the depresslons 89d and 93d of the ri~ng member 89 and the annular gear 93, As shown in Fig. 6, a limit switch 133 and a dog mem-ber 135 are provided on a portion of the frame 3 of the press 1 in the vicinity of the clutch ring 95. The limit switch 133 is so arranged as to stop t~e motor 15 when touched by the dog mem-ber 135, while the dog mem~er 135 is so provided as to be pushed by the clutch ring 95 into contact with the limit switch 133 when the clutch ring 95 is moved out of engagement with the de-pressions 39d and 93d of the ring member 89 and the annular gear 93. In the preferred embodiment, the dog member 135 is slidably inserted in a cylindrical case 137 horizontally fixed to the frame 3 of the press 1 and is biased by a spring 139 toward the clutch ring 95, and it is provided at its end with a roller 141 to be touched by the clutch ring 9S. Thus, when the clutch ring 95 is moved out of engagement with the ring member 89 and the annular gear 93 to disconnect the crank shaft 11 from the power source, the dog member 135 is pushed by the clutch ring 95 into contact with the limit s~itch 133 to stop the motor 15 from driving the press 1. Accordingly, once the crank shaft 11 has begun to unintendedly rotate past its upper dead center to allow the ram 7 to unintendedly doubly stroke, not only the crank shaft 11 i5 stopped from being driven by the annular gear 93 but also the press 1 is completely stopped from being driven by the motor 15.
Referring to Figs. 5 and 6, in order to align radial-ly the annular gear 93 in phase with the clutch ring 95, a proximity switch 143 is provided in the vicinity of the annular gear 33 on a bracket 145 fixed to a portion of the frame 3 of the press 1, and an actuating member 14~ for actuating the proximity switch 143 is fixed to the radially outer edge of the outer side of the annul~r gear 93. In the well-known manner, the proximity switch 143 is so arran~ed as to make a slgnal when the actuating member 147 is in the proximity thereof.
Therefore, the actuatin~ member 147 i5 SO located on the annular gear 45 that it may be in the proximity o~ the proximity switch 143 when the claw mem~ers 97 of the clutch ring 95 are in engage-ment with the depressions 89d and 93d o~ the ring member 89 and the annular gear 93 with the crank shaft 11 put in a pre-deter-mined rotational position. Thus, in order to align radially the annular gear 93 in phase with the clutch ring 95 it is only necessary to firstly rotate the crank shaft 11 to the pre-determined rotational posi~ion and then rotate the annular gear 93 on the ring member 89 until the proximity switch 143 signals that the actuating member 14~ has come into the proximity there-of. Incidentally, it is necessary to align radially the clutch ring 95 in phase with the annular gear 93 after the clutch ring 95 has been moved out of engagement with the depressions 89d and 93d of the ring member 89 and the annular gear 93.
As is now apparsnt from the above description, the ram 7 is softly or shocklessly stopped by the counterbalance - means 25 from unintendedly doubly stroking after a completion ,~ of a stroking cycle as soon as the crank shaft 11 begins to rotate past its upper dead center in the second embodiment too. When the crank shaft 11 unintendedly begins to rotate past its upper dead center and the limit switch 83l is actuated by the dog 85' in the same well-known manner as in the first embodiment, the solenoid operated valve 131 is energized to allow the air pre-ssurized in the annular chamber 99 to exhaust therefrom through the passages 121, the grooves 125, the elongate bore 123 of 30 the crank shaft 11 and the swivel joint 127. Accordingly, the annular piston member 101 cannot pull the clutch ring 95 against the springs 117 any more and the clutch ring 95 is pushed by the ~9577S
springs 117 to bring the claw members 97 out of engagement with the depressions 8gd and 93d of the ring member 89 and the annular gear 93. As the result, the ring member~89 is disconnected from the annular gear 93 to stop driving the crank shaft 11, and according-ly the ram 7 is driven no more by the crank shaft 11 and is softly or shocklessly stoppea from doubly stroking by the counterbalance means 25 without damaging any portion of the press 1. Also, as soon as the clutch ring 95 is pushed by the springs 117 away from the ring member 89 and the annular gear 93, the dog member 135 is pushed thereby into contact with the limit switch 133 to stop the motor 15 out of motion. Furthermore, the annular gear 93 and the clutch ring 95 can be radially aligned in phase with each other by firstly putting the crank shaft 11 to a pre-determined rota-tional position and then rotating the annular gear 93 until the ~-actuating member 147 is brought into the proximity of the proxi-mity switch 143.
As has been so far described, according to the present invention, the crank shaft 11 is disconnect from the power source in case that it begins to unintendedly rotate past its upper dead center to allow the ram 7 to doubly stroke after a com-pletion of a stroke. Also, on disconnection of the crank shaft 11 from the power source, the ram 7 is softly or shocklessly stopped from doubly stroking by the counterbalance means 25 without damaging any portion of the press 1.
Although a preferred form of the present invention has been illustrated and described, it should be understood that the device is capable of modification by one skilled in the art without departing from the principles of the invention. Accordingly, the scope of the invention is to be limited only by the claims append-ed hereto.
Claims (24)
1. A press comprising a ram and drive means for effecting working strokes of the ram between a non-working position and a working position, the motion of the drive means being transmitted to the ram by means of a crankshaft which has an upper dead center corresponding to the non-working position of the ram, said drive means incorporating a first clutch operating under normal conditions to engage and disengage the ram from the drive means, the improvement wherein there is provided a normally engaged second clutch means disposed in series with said first clutch means and being capable of disengaging the ram from the drive means, and means for effecting the disengagement of said second clutch means when the crankshaft inadvertently begins to rotate past its upper dead center to prevent the ram inadvertently effecting a working stroke.
2. A press as claimed in claim 1 wherein said means for disengaging the second clutch are operated in response to the output of a sensing device disposed to detect abnormal movement of the crankshaft past said upper dead center position.
3. A press as claimed in claim 2 wherein the crank-shaft is an eccentric shaft.
4. A press as claimed in claim 2 wherein the second clutch is normally pneumatically held in the engaged position.
5. A press as claimed in claim 4 wherein the second clutch comprise a gear rotatably mounted on the crankshaft and in operative connection with the drive means, said gear having on a face thereof a plurality of radially disposed teeth, and a clutch ring slidably mounted on the crankshaft and having teeth to engage those on the gear face, said clutch ring being rotatably fast on the crankshaft whereby when the clutch ring and gear are engaged rotation of the latter effects rotation of the crankshaft.
6. A press as claimed in claim 5 wherein the crank-shaft has an axial bore and said clutch ring is operatively connected to a piston slidable in the bore, said bore being connected to a source of pressurised fluid for urging the piston to a position at which the ring engages the gear, there being also provided means, for example springs, for urging the clutch ring away from the gear when fluid is exhausted from the bore.
7. A press as claimed in claim 6 wherein the crank-shaft is mounted in a hub on a frame of the press r said hub having a first passageway through which the fluid is supplied to the bore when the crankshaft is at the upper dead centre position and a second passageway which allows fluid to be exhausted from the bore through a valve which is arranged to open when the crankshaft inadvertently passes the upper dead centre position.
8. A press as claimed in claim 4 wherein the second clutch means comprises a ring rotatably fast on the crankshaft, a gear operatively associated with the drive means and rotatably mounted on the ring, and a clutch ring slidably mounted on the crankshaft, said ring and gear having teeth formed on the same side faces thereof and said clutch ring having teeth adapted simultaneously to engage the teeth on the side faces of the ring and the gear, whereby, when the second clutch is engaged, rotation of the gear by the drive means effects rotation of the crankshaft.
9. A press as claimed in claim 8 wherein the ring has, on its face opposite that on which its teeth are provided, an annular recess defining a cylinder and an annular piston works in the cylinder, said cylinder being in communication with a source of pressurised fluid and said piston being operatively associated with the clutch ring whereby, when pressurised fluid is supplied to the cylinder, the piston moves to bring the clutch ring into engagement with the ring and gear.
10. A press as claimed in claim 9 wherein springs are provided for biasing the clutch ring away from the ring and gear.
11. A press as claimed in claim 9 wherein the piston is mounted on a disc plate locating over the end of the crank-shaft, and said piston is operatively associated with the clutch ring by means of bolts or the like connecting the clutch ring and the disc plate.
12. A press as claimed in claim 11 wherein the crankshaft has an axial bore, the disc plate has a passageway communicating between the bore and the cylinder and the source of pressurised fluid is connected to the bore of the crank-shaft.
13. A press as claimed in any one of claims 9 to 11 wherein fluid is supplied to and exhausted from the cylinder via a common solenoid valve, and said valve is operated to allow exhaustion of fluid by a limit switch which is operated by means on the crankshaft when the crankshaft unintendedly rotates past its upper dead centre.
14. A press as claimed in any one of claims 9 to 11 wherein means are provided for arresting the drive means when the clutch ring is disengaged from the ring and gear.
15. A press as claimed in any one of claims 8 to 10 wherein a proximity switch is provided to facilitate alignment of the gear and the clutch ring.
16. A press as claimed in any one of claims 1-3 and further comprising counterbalance means for the ram.
17. A mechanical press comprising a press ram mounted on a crankshaft adapted for reciprocatory movement along a vertical path between uppermost and lowermost points on said path, motor means operatively coupled to said crank-shaft for turning said crankshaft through 360° rotation includ-ing an upper dead centre position, main clutch and brake means for disconnecting said crankshaft from said motor means and stopping said ram at said uppermost point after completion of a stroking cycle when said crankshaft is at said upper dead centre position auxiliary clutch means operatively con-nected in series with said main clutch means and which is normally engaged for transmitting power from said motor means to said crankshaft, and means for automatically disengaging said auxiliary clutch means if said crankshaft unintentionally rotates past said upper dead centre position upon completion of a stroking cycle of said ram.
18. A mechanical press as defined in claim 17, and further including counterbalance means for shocklessly and gradually stopping said ram after disengagement of said auxiliary clutch means.
19. A mechanical press as defined in claim 17 wherein said means for automatically disengaging said auxiliary clutch means includes resilient means biasing said auxiliary clutch means toward the disengaged position thereof, pneumatic means opposing the force of said resilient means and normally maintaining said auxiliary clutch means in the engaged posi-tion thereof, and means for venting said penumatic means if said crankshaft unintentionally rotates past said upper dead centre position upon completion of a stroking cycle of said ram thereby permitting said resilient means to disengage said auxiliary clutch means.
20. A mechanical press as defined in claim 19, wherein said pneumatic means includes a piston disposed within a cylinder and operatively opposing said resilient means, means for connecting said cylinder to a source of pneumatic fluid for urging said piston against said resilient means, said venting means including means connecting said cylinder with the atmosphere, solenoid-operated valve means for normally maintaining said cylinder closed to the atmosphere, and switch means for energizing said solenoid-operated valve means to open said cylinder to the atmosphere when said crankshaft unintentionally rotates a predetermined number of degrees past said upper dead centre position thereof upon completion of a stroking cycle of said ram.
21. A mechanical press as defined in claim 20, wherein said means connecting said cylinder with the atmosphere includes port means radially extending through said crankshaft and communicating with said solenoid-operated valve.
22. A mechanical press as defined in claim 20, wherein said piston is an annular member and said cylinder is an annular chamber, said means for connecting said cylinder to a source of pneumatic fluid includes an elongate bore ex-tending longitudinally through said crank shaft, and wherein said solenoid-operated valve connects said annular chamber to said source of pneumatic fluid when not energized and connects said annular chamber to the atmosphere when energized.
23. A mechanical press as defined in claim 22, and further including limit switch means operatively connected to said auxiliary clutch means for stopping said motor means upon disengagement of said auxiliary clutch means.
24. A method of preventing unintended repeated strokes of the ram during operation of a mechanical press upon failure of the main clutch or the like wherein the ram is mounted on a crank shaft and adapted for reciprocatory move-means along a vertical path between uppermost and lowermost points on the path, and wherein the crank shaft is rotatable through 360 degrees and the main clutch is disengageable to stop the ram after the completion of a stroking cycle at the uppermost point thereof when the crank shaft is at the upper dead centre position thereof, comprising the steps of:
(a) providing an auxiliary clutch which is normally engaged for transmitting power to the crankshaft;
(b) sensing when the crankshaft uninten-tionally rotates past the upper dead centre position thereof upon completion of a stroking cycle of the ram;
(c) generating a signal indicative of said sensing step; and (d) automatically disengaging said auxiliary clutch in response to said signal to prevent an unintended stroking cycle of said ram.
(a) providing an auxiliary clutch which is normally engaged for transmitting power to the crankshaft;
(b) sensing when the crankshaft uninten-tionally rotates past the upper dead centre position thereof upon completion of a stroking cycle of the ram;
(c) generating a signal indicative of said sensing step; and (d) automatically disengaging said auxiliary clutch in response to said signal to prevent an unintended stroking cycle of said ram.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15744176A JPS5383174A (en) | 1976-12-28 | 1976-12-28 | Safty method of preventing accidentally continuous operation of press and apparatus therefor |
| JP157441 | 1976-12-28 | ||
| JP34024/1977 | 1977-03-29 | ||
| JP3402477A JPS53119480A (en) | 1977-03-29 | 1977-03-29 | Safty means for preventing accidentally continuous operation of press |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1095775A true CA1095775A (en) | 1981-02-17 |
Family
ID=26372813
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA293,909A Expired CA1095775A (en) | 1976-12-28 | 1977-12-23 | Method and devices for safety for mechanical presses |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4190143A (en) |
| CA (1) | CA1095775A (en) |
| DE (1) | DE2757636C2 (en) |
| FR (1) | FR2375982A1 (en) |
| GB (1) | GB1598359A (en) |
| IT (1) | IT1091629B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4186827A (en) * | 1978-06-22 | 1980-02-05 | Gulf & Western Manufacturing Company | Fluid operated clutch and brake |
| US4372202A (en) * | 1980-11-20 | 1983-02-08 | Ross Operating Valve Company | Emergency brake for presses |
| US4457418A (en) * | 1981-11-19 | 1984-07-03 | Black & Webster, Inc. | Safety system |
| GB2187125B (en) * | 1986-02-06 | 1990-10-03 | Amada Co Ltd | Punch press |
| KR200177090Y1 (en) * | 1998-04-04 | 2000-04-15 | 허명호 | Urgent braking appratus of power press |
| CN106694746B (en) * | 2016-12-30 | 2018-06-29 | 重庆大友金属有限责任公司 | Plate stamping method |
| CN106825309B (en) * | 2016-12-30 | 2018-07-06 | 重庆大友金属有限责任公司 | Plate stamping device |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE7437478U (en) * | 1975-10-30 | Maschinenfabrik Weingarten Ag | Device for securing passage for eccentric presses, punches, scissors or similar machines with clutch and brake | |
| DE1739352U (en) * | 1956-10-31 | 1957-02-07 | Weingarten Ag Maschf | ARRANGEMENT FOR COMPRESSED AIR CONTROL FOR PRESSING, PUNCHING OR. DGL. |
| US3113653A (en) * | 1960-09-16 | 1963-12-10 | Volkovitsky Valent Feodorovich | Apparatus for freeing a jammed press ram |
| DE1933460U (en) * | 1965-12-17 | 1966-02-24 | Wolff Fa Gustav | HYDRAULICALLY OPERATED CONTROL FOR WORK MACHINES, IN PARTICULAR ECCENTRIC PRESSES OR CRANK PRESSES. |
| US3504774A (en) * | 1967-09-25 | 1970-04-07 | Dro Systems Inc Di | Structure for and method of driving a metal working press |
| DE6752065U (en) * | 1968-08-26 | 1969-02-20 | Weingarten Ag Maschf | MECHANICALLY ACTIVATED STOP DEVICE FOR PRESSES WITH ELECTRO-PNEUMATIC FRICTION CLUTCH AND BRAKE |
| US3509976A (en) * | 1968-10-11 | 1970-05-05 | Textron Inc | Single cycle control system with anti-repeat means |
| US3613357A (en) * | 1969-07-10 | 1971-10-19 | Clinton E Withington | Non-repeat control apparatus for power machinery |
| DE2155864B2 (en) * | 1971-11-10 | 1975-12-18 | L. Schuler Gmbh, 7320 Goeppingen | Safety inpact absorber for presses and/or punches - includes flat component which becomes corrugated under overload |
| DE2312870C3 (en) * | 1973-03-15 | 1978-06-08 | Maschinenfabrik Weingarten Ag, 7987 Weingarten | Pressure fluid operated friction clutch and braking device for presses, punching or shearing |
| DE2453946A1 (en) * | 1974-11-14 | 1976-06-16 | Schuler Gmbh L | Mechanical press with two brakes - which can be operated separately |
| DE2454865A1 (en) * | 1974-11-20 | 1976-08-12 | Weingarten Ag Maschf | Safety device for traverse of forging press - has additional brake device operating simultaneously with compressed air supply line exhaust |
| DE2541174C3 (en) * | 1975-09-16 | 1978-06-01 | Maschinenfabrik Weingarten Ag, 7987 Weingarten | Pass-through protection for eccentric and related presses with a clutch-braking device that works with friction linings |
-
1977
- 1977-12-23 CA CA293,909A patent/CA1095775A/en not_active Expired
- 1977-12-23 DE DE2757636A patent/DE2757636C2/en not_active Expired
- 1977-12-23 GB GB53831/77A patent/GB1598359A/en not_active Expired
- 1977-12-28 IT IT69929/77A patent/IT1091629B/en active
- 1977-12-28 FR FR7739508A patent/FR2375982A1/en active Granted
- 1977-12-28 US US05/865,191 patent/US4190143A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| FR2375982A1 (en) | 1978-07-28 |
| DE2757636A1 (en) | 1978-06-29 |
| DE2757636C2 (en) | 1985-09-19 |
| FR2375982B1 (en) | 1983-01-28 |
| GB1598359A (en) | 1981-09-16 |
| US4190143A (en) | 1980-02-26 |
| IT1091629B (en) | 1985-07-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |